Well, I think we should look at it from the perspective of a non-helmet. Let's use Michigan State so that this thread can be a #safespace and not #trigger Badge with discussions of Wisconsin's scheduling woes.
Going to 8 gives a team like MSU two potential paths to getting into the CFP:
Assume MSU schedules strong OOC, and we'll use Purdue's OOC this year as an example. Purdue played Missouri, Eastern Michigan, and a ranked Boston College. Not scheduling the best of the best, of course, but a pretty solid schedule when you consider they're playing 9 conference games.
- Win your conference.
- Get an at-large bid.
Let's say MSU goes 1-2 against that slate, losing to the two P5 teams, but goes 8-1 and wins the CCG: they're in at 10-3 overall. There was ZERO downside to scheduling tough OOC. At worst they'll be badly-seeded in the CFP.
Now let's say MSU goes 3-0 against that slate. They then go 8-1 in conference but due to tiebreakers, don't go to the CCG. Now they're 11-1 with a strong OOC and their only loss was to a team that went to the CCG: they have an EXCELLENT argument for one of the at-large berths. So they are HELPED by scheduling tough OOC.
So in both of those cases the strong OOC either didn't hurt them or actively helped them. Assume MSU schedules 2 MAC teams and one FCS OOC.
Let's say they go 3-0 OOC, and they go 8-1 in conference, plus win the CCG. At 12-1, their weak OOC schedule and non-helmet status will probably impact their seeding negatively. So even though they'll be in, they won't be a top seed.
Now let's say they go 3-0 OOC, but 8-1 in conference, but don't go to the CCG due to tiebreaker, or like Iowa in 2015, go 9-0 and get to the CCG and perhaps lose to a weaker team from the West. They'll be 11-1 or 12-1, but don't have a conference championship, have a weak OOC slate, and they're not a helmet. There will be easy arguments for another team with similar resume and stronger OOC games to take one of those at-large spots.
I personally think teams will be helped more than they're hurt by scheduling strong OOC. If you win your conference, it doesn't hurt you at all. If you come CLOSE to winning your conference, a strong OOC can put you over the edge for the at-large selection. And having a weak OOC if you don't win your conference could push you under the line and miss out on that at-large selection, even if you win those games.